Latchable roller actuated plunger switch mounted in a welding torch handle



Aug. '18,- 1970 aw W e Z m w 7 m% K H 8 H1 m. m n i i: l c m mm A vb I lm we a IIm W 1/ AF N LATCHABLE ROLLER ACTUATED PLUNGER SWITCH MO UnitedStates Patent 3,524,955 LATCHABLE ROLLER ACTUATED PLUNGER SWITCH MOUNTEDIN A WELDING TORCH HANDLE Eugene Karpinski, New Berlin, Wis., assignorto Machinery and Welder Manufacturing Corporation, Greendale, Wis., acorporation of Wisconsin Filed Dec. 21, 1967, Ser. No. 692,548 Int. Cl.H01h 9/ 06 US. Cl. 200--157 4 Claims ABSTRACT OF THE DISCLOSURE A switchhousing has a resiliently biased, reciprocally movable plunger mountedtherein which closes a circuit, in the retracted or in position. Adepressible, fingeractuatable lever or switch actuator is pivotallymounted on said housing and has a roller or the like mounted on one endportion thereof which is adapted to engage the plunger distal end andaxially move the same inwardly in the course of lever depression. Anabutment is adjustably positionable between said lever and housing,limiting the extent of pivotal movement of said lever and the resultingcontact between the roller and plunger.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to improvements in switch assemblies. More particularly itpertains to switch assemblies normally found on manually engageablehandle portions of apparatus such as the handles of a welding torch inwhich the making and breaking of an electrical circuit is desired fortime periods of irregular length.

Description of the prior art The prior art discloses switchconstructions disposed on the handle portions of welding torches or thelike as in Meyer Us. Letters Patent No. 3,249,734. In the constructiondisclosed in this patent, however, the switch is never closed unlesspressure is applied to a hand-engageable lever or switch actuator. Thus,when the switch is to remain closed for an extended period of time,pressure must be constantly applied, which application may on occasionlead to uncomfortable fatigue or cramping of the welders hand.

The prior art switch constructions are generally complex in structurebeing composed of many parts which may be of unusual design and thusreplaceable, if at all, with difficulty. Normally the known switches fortorches or the like are not possessed of flexibility in operation andsimplicity of construction such as are embodied in the providedconstruction.

SUMMARY It is an object of this invention, therefore, to provide anadjustable switch assembly which is readily positionable into aconstantly closed position thereby rendering pressure applicationunnecessary. The provided switch may also be readily adjusted into aposition in which constant finger pressure is necessary to maintain theswitch closed whereby the circuit controlled by the switch may beinstantaneously closed or opened.

It is another object of this invention to provide a novel switchassemblyin which a roller, or the like, actuator for a resiliently biased switchplunger mounted on a pivotal lever arm is controlled in the course ofits pivotal movement relative to said resiliently biased plunger bymeans of an abutment positioned between said lever arm and the switchhousing on which said plunger is mounted.

A further object is to provide a switch assembly which is readilyadjustable, operable and repairable, being composed of a minimum numberof parts of basic design.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a weldingtorch employing the switch assembly of this invention.

FIG. 2 is an enlarged side elevational view of the switch assembly ofFIG. 1 in one operational position, illustrat-.

DETAILED DESCRIPTION Referring now to FIG. 1 of the drawing, a weldingtorch 10 is illustrated comprising a hollow tubular handle 12 composedof insulating material and a metallic welding tip means 14 connected tothe handle. A nozzle body member 16 engages an insulation bushing 18 andis engaged at its opposed end by gas cup 20. A terminal portion of acontact tip means 22 is shown projecting from the open end of the gascup.

The torch 10 is of the type used in a continuous welding apparatus andaccordingly employs a power cable 24, a gas-feeding conduit 26, aninsulation-covered conduit 28 adapted to carry welding wire, and aswitch cord 30 connected to switch assembly 32.

The invention herein presented is directed to the switch assembly whichmay be employed in torch constructions such as are disclosed in thecopending applications Ser. Nos. 692,585 and 658,110, filed Dec. 21,1967 and Aug. 3, 1967, respectively, and entitled Handle Constructionand Welding Torch for Continuous Welding Apparatus, respectively.

Actuation of the switch of switch assembly 32 closes circuits forenergizing a drive mechanism (not illustrated) for feeding welding wire(not illustrated) through the conduit 28 and tip means 22 and forsupplying welding current through power cable 24. Also, mechanism (notillustrated) is energized which passes gas through the conduit 26 andgas cup 20.

It is apparent that in the normal course of use a welding torch such astorch 10 is employed for irregular time periods. Thus if a long weld ofa continuous nature is to be made, it is essential that the energizingswitch be maintained closed so that the appropriate mechanism employedin conjunction with the torch may be maintained energized. In the courseof effecting such a long weld, it

would be desirable if switch 36 of the switch assembly 32 weremaintained in a closed position without the necessity of continuallyapplying finger pressure to the actuator arm 34 which effects closing ofthe switch. Also it is apparent that if the torch is to be employed atshort irregular intervals, it is desirable that the welder be able toenergize and de-energize the apparatus employed in conjunction with thetorch by instantaneous finger actuation of the lever arm 34.

Utilizing the switch assembly 32 of this invention, the lever arm 34 maybe readily positioned so as to maintain switch 36 of the assembly 32,more clearly seen in FIGS. 2, 3 and 5, in a closed position without thenecessity of constantly applying finger pressure. Switch 36 includes areciprocally movable plunger 38 which is composed of electricallyinsulating material and is resiliently biased, as by a coil spring orthe like disposed within switch body 40, into an extended position. Whenthe plunger 38 is in such position, the switch 36 is open and theelectrical circuits controlled thereby are inoperative. When the plungeris forced to retract into switch body 40 in opposition to the springmember (not illustrated) the switch 36 is closed and the circuitscontrolled thereby are operational.

It will be more clearly seen from FIGS. 2, 3 and that switch 36 isretained to the apertured flange portion 44 of switch housing 42 bymeans of a nut 46 which engages threaded portion 48 of the switch andholds an opposed portion 50 of the body 40 against the flange 44.

As is seen from FIG. 1, lever arm 34 is readily engageable by thefingers of the welder as he grasps the handle portion 12 of the torch.The lever arm 34 is pivotally mounted on switch housing 42 by means ofpin 52 as is most apparent from FIGS. 2, 3 and 5. Mounted on the endportion of the lever arm 34, which is adjacent the switch plunger 38, isa roller 54 of durable, electrically insulating material. The roller 54is rotatably mounted on a transverse pin 56 extending between opposedtwin mounting portions 58 of the lever arm.

As is apparent from FIG. 2, the end of plunger 38 engages the roller 54below and rearwardly of its axis thereby tending to hold the lever arm34 in the upward position. As the lever arm 34 is depressed, roller 54will engage the resiliently biased plunger 38 forcing the same toretract into the body of the switch 36 (i.e., closes the switch). Itwill also be noted, by comparing FIGS. 2 and 3, that as the switch leverarm is depressed further, the plunger 38 passes above the axis ofrotation of the roller 54 (FIG. 3). In this position, the lever arm 34will be locked in a fixed position relative to the switch housing 42,and the switch remains locked in closed position. The roller 54 andplunger 38 comprise, in essence, an over-center device. To open theswitch 36, it is necessary to depress the rear portion 34a of the leverarm 34 which pivots clockwise about pin 52 and causes the plunger toassume the position shown in FIG. 2.

In accordance with the invention, when it is desirable to have theplunger 38 of the switch 36 under the immediate control of the welder,an adjustable abutment 60 and its locking screw 62, more clearly seen inFIGS. 2, 3 and 5 are moved along a slot 63 (FIG. 4) which is formed inthe upper surface of lever arm 34 over the roller 54.

The locking screw 62 engages a tapped hole in the abutment thereby tolock the abutment at either of two desired positions along the length ofthe slot 63. When the abutment and screw are moved to the right asillustrated in solid lines in FIG. 5 and in dotted lines in FIG. 4, theabutment 60 will be in a position to contact the upper surface of theswitch housing 42 as will be most apparent from FIG. 5. The lever arm 34may then be depressed only to a limited extent toward the underlyingswitch housing and handle 12. That is, the abutment 60 in the positionof FIG. 5 will prevent the resiliently mounted plunger 38 of the switch36 from passing beyond the axis of rotation of the roller 54. But, itwill still enable the lever arm 34 to be depressed to a sufficientdegree so as to move the plunger 38 inwardly to elfect desired closingof the circuit control switch.

If the welder employing the torch 10 is desirous of having the switch 36in a closed position for an extended period of time, he will move theabutment 60 and screw 62 to the left end portion of the slot 63 in themanner illustrated in full line in FIG. 4 and in FIGS. 2 and 3. In thisposition the abutment does not prevent the lever arm from movingdownwardly to the full extent.

correspondingly, if a welder desires momentary con trol of the switch36, the abutment 60 of the switch assembly will be moved to the positionof FIG. 5.

The provided switch assembly 32 is composed of a minimum number ofsimple and readily replaceable parts. The assembly 32 may be readilydisengaged from the handle 12 of the torch 10 by removing two retainingscrews 64 which readily engage tapped holes in the handle 12 aftertraversing apertures 66 of flanges 68 of the housing, see FIGS. 2, 3 and5.

While particular embodiments of this invention have been shown anddescribed, it will be understood, of course, that the invention is notlimited thereto since modifications may be made by those skilled in theart, particularly in light of the foregoing teachings. Therefore, it iscontemplated by the appended claims to cover any such modifications asincorporate those features which may be said to constitute the essentialfeatures of these improvements, within the true spirit and scope of theinvention.

What is claimed is:

1. In a welding torch or the like having a manually engageable handle, aswitch assembly mounted on said handle; said switch assembly having ahousing, means for connecting said housing to said handle, afinger-engageable lever pivotally mounted on said housing and pivotableabout an arcuate path into a depressed position adjacent said handle, anextensible, resiliently-biased plunger mounted on said housing; rollermeans pivotally mounted on said lever adapted to engage said plunger andforce the same into a retracted position when said lever is in adepressed position; said roller being so located relative to saidplunger that its pivot point may cross the longitudinal axis of saidplunger as said lever is pivoted from its normal to its depressedposition; an adjustable stop means interposed said lever and housing forregulating the extent to which said lever may be depressed.

2. The switch assembly according to claim 1 in combination with meansfor locking said adjustable stop means in a position whereby saidplunger may engage roller portions on only one side of said commonplane.

3. The switch assembly according to claim 1 wherein said adjustable stopmeans comprises a reciprocally movable abutment mounted in an uppersurface portion of said lever disposed over said roller.

4. In a welding torch or the like having a manually engageable handle, aswitch assembly mounted on said handle; said switch assembly comprisinga switch housing, a switch mounted on said housing means detachablysecuring said housing to said handle, a finger-engageable lever mountedon said housing and movable in the direction of said underlying handleinto a depressed position; said switch having an extensible,resiliently-biased plunger reciprocally movable along a longitudinalaxis into positions which open and close an electrical circuitcontrolled by said switch, a roller mounted on said lever with its axisof rotation disposed substantially transversely to the plunger axis andadapted to have an arcuate surface portion thereof strike the distal endof said plunger whereby an axial force component is imparted to saidplunger forcing the same to retract into said switch when said levermoves into a depressed position; adjustable, sliding stop means mountedon said lever for regulating the extent of which said lever may bedepressed in one position of adjustment; the axis of rotation of saidroller passing across said plunger longitudinal axis with said stopmeans in another position of adjustment whereby said lever is locked inplace and may not return to its initial position without being urgedagainst said biased plunger thereby forcing the same to retract toenable the roller axis of rotation to pass across said plungerlongitudinal axis; the electrical circuit controlled by said switchassembly being closed when said lever is in the locked position.

References Cited UNITED STATES PATENTS 2,701,288 2/1955 Russell et al.2,812,418 11/1957 Allan et al. 200-157 X 6 3,117,208 1/1964 Svensson200I 69 3,379,852 4/ 1968 Korshak 200-157 1,424,402 8/ 1922 Hartman200-68 X FOREIGN PATENTS 802,827 10/ 1958 Great Britain.

378,976 8/1964 Switzerland.

962,745 7/1964 Great Britain.

0 ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERHYE, AssistantExaminer U.S. Cl. X.R.

